. Bulletin. Science. Figure 24.—James Joseph Sylvester (1814-1897), mathematician and lec- turer on straight-line linkages. From Proceedings of the Royal Society of London (i8g8, vol. 63, opposite p. 161). Charles-Nicolas Peaucellier, a graduate of the Ecole Polytechnique and a captain in the French corps of engineers, was 32 years old in 1864 when he wrote a short letter to the editor of Nouvelles Annales de mathematiques (ser. 2, vol. 3, pp. 414-415) in Paris. He called attention to what he termed "compound compasses," a class of linkages that included Watt's parallel motion, the p
. Bulletin. Science. Figure 24.—James Joseph Sylvester (1814-1897), mathematician and lec- turer on straight-line linkages. From Proceedings of the Royal Society of London (i8g8, vol. 63, opposite p. 161). Charles-Nicolas Peaucellier, a graduate of the Ecole Polytechnique and a captain in the French corps of engineers, was 32 years old in 1864 when he wrote a short letter to the editor of Nouvelles Annales de mathematiques (ser. 2, vol. 3, pp. 414-415) in Paris. He called attention to what he termed "compound compasses," a class of linkages that included Watt's parallel motion, the pantograph, and the polar planimeter. He proposed to design linkages to describe a straight line, a circle of any radius no matter how large, and conic sections, and he indicated in his letter that he had arrived at a solution. This letter stirred no pens in reply, and during the next 10 years the problem merely led to the filling of a few academic pages by Peaucellier and Amedee Mannheim (1831-1906), also a graduate of Ecole Polytechnique, a professor of mathematics, and the designer of the Mannheim slide rule. Finally, in 1873, Captain Peaucellier gave his solution to the readers of the Nouvelles Annales. His reasoning, which has a distinct flavor of discovery by hindsight, was that since a linkage generates a curve that can be expressed algebraically, it must follow that any algebraic curve can be generated by a suitable link- age—it was only necessary to find the suitable linkage. He then gave a neat geometric proof, suggested by Mannheim, for his straight-line "compound com- pass. On a Friday evening in January 1874 Albemarle Street in London was filled with carriages, each *2 Charles-Nicholas Peaucellier, "Note sur une question de geometrie de compas," Nouvelles Annales de mathematiques, 1873, ser. 2, vol. 12, pp. 71—78. A sketch of Mannheim's work is in Florian Cajori, A History 0] the Logarithmic Slide Rule, New York, about 1910, reprinted in String
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